It is well to fetter the wings of our fancy and restrain its flights. It
is quite possible we may have formed entirely erroneous ideas of what we
actually see. The greenish gray patches may not be seas at all, nor the
ruddy continents, solid land. Neither may the obscuring patches be
clouds of vapor. Man is too quick at forming conclusions. Let him but
indistinctly see a thing, or even be undecided as to whether he does
actually see it and he will then and there set himself to theorizing,
and build immense castles of conjecture on a foundation, of whose
existence he is by no means certain.

— Edward Emerson Barnard, Mars: His Moons and His Heavens, an
unpublished manuscript in the Vanderbilt University Archives, 1880.

Speculation has been singularly fruitful as to what these markings on
our next to nearest neighbor in space may mean. Each astronomer holds a
different pet theory on the subject, and pooh-poohs those of all the
others. Nevertheless, the most self-evident explanation from the
markings themselves is probably the true one; namely, that in them we
are looking upon the result of the work of some sort of intelligent
beings… . The amazing blue network on Mars hints that one planet
besides our own is actually inhabited now.

— Percival Lowell, address to the Boston Scientific Society, printed
in the Boston Commonwealth. This was before he want to Flagstaff and
viewed Schiaparelli's network of canali for himself. 22 May 1894.

Are physical forces alone at work there, or has evolution begotten
something more complex, something not akin to what we know on Earth
as life? It is in this that lies the peculiar interest of Mars.

— Percival Lowell, Mars, 1895.

Irrigation, unscientifically conducted, would not give us such truly
wonderful mathematical fitness [as we observe in the Martian canals]… . A mind of no mean order would seem to have presided over the system
we see — a mind certainly of considerably more comprehensiveness than that
which presides over the various department of our own public works.

— Percival Lowell, c. 1908.

Mars, therefore, is not only uninhabited by intelligent beings such
as Mr. Lowell postulates, but is absolutely uninhabitable.

— Alfred Russel Wallace, last sentence of his book Is Mars
Habitable, 1907.

There are celestial sights more dazzling, spectacles that inspire more
awe, but to the thoughtful observer who is privileged to see them well,
there is nothing in the sky so profoundly impressive as the canals of
Mars. Fine lines and little gossamer filaments only, cobwebbing the face of the Martian disk, but threads to draw one's mind after them across the millions of miles of intervening void.

— Percival Lowell, Mars as the Abode of Life, 1908.

[scientists have] discovered two lesser stars, or satellites, which
revolve about Mars; whereof the innermost is distant from the center of
the primary planet exactly three of its diameters, and the outermost
five; the former revolves in the space of ten hours, and the latter in
twenty one and a half; so that the squares of their periodical times are
very near in the same proportion with the cubes of their distance from
the center of Mars; which evidently shows them to be governed by the
same law of gravitation that influences the other heavenly bodies.

— Jonathan Swift, Gulliver's Travels, the moons of Mars could not
be observed at this time, 1726.

The logistic requirements for a large, elaborate mission to Mars are
no greater that those for a minor military operation extending over
a limited theatre of war.

— Wernher von Braun, The Mars Project, written in German in
1948, published as Das Marsprokekt in 1952, first English
edition published in 1953.

In 1492 Columbus knew less about the far Atlantic than we do about
the heavens, yet he chose not to sail with a flotilla of less than
three ships… . So it is with interplanetary exploration: it must
be done on the grand scale.

— Wernher von Braun, The Mars Project, written in German in
1948, published as Das Marsprokekt in 1952, first English
edition published in 1953.

Today we haved touched Mars. There is life on Mars, and it us
us — extensions of our eyes in all directions, extensions of our mind,
extensions of our heart and soul have touched Mars today. That's the
message to look for there: We are on Mars. We are the Martians!

— Ray Bradbury, science fiction author, speaking at The Search
for Life in our Solar System, a symposium at the Jet Propulsion
Laboratory, Pasadena, California, 8 October 1976.

We have your satellite if you want it back send 20 billion in Martian
money. No funny business or you will never see it again.

— Reportedly seen on a wall in a hall at NASA's Jet
Propulsion Laboratory, Pasadena, California, after losing contact with the Mars Polar
Lander, 1999.

If a dog had shit on the ground one meter from a Viking
lander, it would never have detected it.

We have concluded that the rocks here were once
soaked in liquid water. It changed their texture, and it changed
their chemistry. We've been able to read the tell-tale clues the
water left behind, giving us confidence in that conclusion.

We are all … children of this universe. Not just
Earth, or Mars, or this system, but the whole grand fireworks. And if we
are interested in Mars at all, it is only because we wonder over our
past and worry terribly about our possible future.

— Ray Bradbury, Mars and the Mind of Man, 1973.

‎If it's a new planet, sign me up. I'm tired of driving around the
block, boldly going where hundreds have gone before in orbit around
earth — give me a place to go and I'll go.

— Neil deGrasse Tyson, astrophysicist and
director of the Hayden Planetarium, regards a manned mission to
Mars. TV interview on The Daily Show With Jon Stewart, 18
January 2011

It was obvious to me that we could never colonize Mars without reusability, any more than America would have been colonized if they had to burn the ships after every trip.